1. Field of the Invention
The present invention relates to a test structure for electron beam inspection and a method for defect determination using electron beam inspection, and more particularly, to a test key structure having a cap dielectric layer disposed on a connection structure and a method for defect determination using a lock-in amplifier to amplify signals received by an instant detector.
2. Description of the Prior Art
Semiconductor integrated circuits undergo a variety of processing steps during manufacture, such as masking, resist coating, etching, and deposition. The interconnections between different material layers must be effective for properly operating the semiconductor device, and defects generated in the manufacturing processes have to be monitored for improving the manufacturing yield.
Recently, electron beam (e-beam) inspection (EBI) tool has been applied to detect defects in the semiconductor wafer. For example, voltage-contrast type defects, such as electrical shorts or opens at a contact or a void in the interconnections may be detected by the e-beam inspection tool. However, the e-beam inspection tool has very poor capability on high-resistance defect mode due to relatively weak signals from poor signal-to-noise ratio (S/N ratio) and small gray level value difference (ΔGLV), and there is no other index for further judging the degree of the failure.